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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
"use strict";
var EXPORTED_SYMBOLS = ["GoogleTranslator"];
const { Services } = ChromeUtils.import("resource://gre/modules/Services.jsm");
const { PromiseUtils } = ChromeUtils.import(
);
const { httpRequest } = ChromeUtils.import("resource://gre/modules/Http.jsm");
// The maximum amount of net data allowed per request on Google's API.
const MAX_REQUEST_DATA = 5000; // XXX This is the Bing value
// The maximum number of chunks allowed to be translated in a single
// request.
const MAX_REQUEST_CHUNKS = 128; // Undocumented, but the de facto upper limit.
// Self-imposed limit of 15 requests. This means that a page that would need
// to be broken in more than 15 requests won't be fully translated.
// The maximum amount of data that we will translate for a single page
// is MAX_REQUESTS * MAX_REQUEST_DATA.
const MAX_REQUESTS = 15;
/**
* Translates a webpage using Google's Translation API.
*
* @param translationDocument The TranslationDocument object that represents
* the webpage to be translated
* @param sourceLanguage The source language of the document
* @param targetLanguage The target language for the translation
*
* @returns {Promise} A promise that will resolve when the translation
* task is finished.
*/
var GoogleTranslator = function(
translationDocument,
sourceLanguage,
targetLanguage
) {
this.translationDocument = translationDocument;
this.sourceLanguage = sourceLanguage;
this.targetLanguage = targetLanguage;
this._pendingRequests = 0;
this._partialSuccess = false;
this._translatedCharacterCount = 0;
};
GoogleTranslator.prototype = {
/**
* Performs the translation, splitting the document into several chunks
* respecting the data limits of the API.
*
* @returns {Promise} A promise that will resolve when the translation
* task is finished.
*/
async translate() {
let currentIndex = 0;
this._onFinishedDeferred = PromiseUtils.defer();
// Let's split the document into various requests to be sent to
// Google's Translation API.
for (let requestCount = 0; requestCount < MAX_REQUESTS; requestCount++) {
// Generating the text for each request can be expensive, so
// let's take the opportunity of the chunkification process to
// allow for the event loop to attend other pending events
// before we continue.
await new Promise(resolve => Services.tm.dispatchToMainThread(resolve));
// Determine the data for the next request.
let request = this._generateNextTranslationRequest(currentIndex);
// Create a real request to the server, and put it on the
// pending requests list.
let googleRequest = new GoogleRequest(
request.data,
this.sourceLanguage,
this.targetLanguage
);
this._pendingRequests++;
googleRequest
.fireRequest()
.then(this._chunkCompleted.bind(this), this._chunkFailed.bind(this));
currentIndex = request.lastIndex;
if (request.finished) {
break;
}
}
return this._onFinishedDeferred.promise;
},
/**
* Function called when a request sent to the server completed successfully.
* This function handles calling the function to parse the result and the
* function to resolve the promise returned by the public `translate()`
* method when there's no pending request left.
*
* @param request The GoogleRequest sent to the server.
*/
_chunkCompleted(googleRequest) {
if (this._parseChunkResult(googleRequest)) {
this._partialSuccess = true;
// Count the number of characters successfully translated.
this._translatedCharacterCount += googleRequest.characterCount;
}
this._checkIfFinished();
},
/**
* Function called when a request sent to the server has failed.
* This function handles deciding if the error is transient or means the
* service is unavailable (zero balance on the key or request credentials are
* not in an active state) and calling the function to resolve the promise
* returned by the public `translate()` method when there's no pending.
* request left.
*
* @param aError [optional] The XHR object of the request that failed.
*/
_chunkFailed(aError) {
this._checkIfFinished();
},
/**
* Function called when a request sent to the server has completed.
* This function handles resolving the promise
* returned by the public `translate()` method when all chunks are completed.
*/
_checkIfFinished() {
// Check if all pending requests have been
// completed and then resolves the promise.
// If at least one chunk was successful, the
// promise will be resolved positively which will
// display the "Success" state for the infobar. Otherwise,
// the "Error" state will appear.
if (--this._pendingRequests == 0) {
if (this._partialSuccess) {
this._onFinishedDeferred.resolve({
characterCount: this._translatedCharacterCount,
});
} else {
this._onFinishedDeferred.reject("failure");
}
}
},
/**
* This function parses the result returned by Bing's Http.svc API,
* which is a XML file that contains a number of elements. To our
* particular interest, the only part of the response that matters
* are the <TranslatedText> nodes, which contains the resulting
* items that were sent to be translated.
*
* @param request The request sent to the server.
* @returns boolean True if parsing of this chunk was successful.
*/
_parseChunkResult(googleRequest) {
let results;
try {
let response = googleRequest.networkRequest.response;
results = JSON.parse(response).data.translations;
} catch (e) {
return false;
}
let len = results.length;
if (len != googleRequest.translationData.length) {
// This should never happen, but if the service returns a different number
// of items (from the number of items submitted), we can't use this chunk
// because all items would be paired incorrectly.
return false;
}
let error = false;
for (let i = 0; i < len; i++) {
try {
let result = results[i].translatedText;
let root = googleRequest.translationData[i][0];
if (root.isSimpleRoot && result.includes("&")) {
// If the result contains HTML entities, we need to convert them as
// simple roots expect a plain text result.
let doc = new DOMParser().parseFromString(result, "text/html");
result = doc.body.firstChild.nodeValue;
}
root.parseResult(result);
} catch (e) {
error = true;
}
}
return !error;
},
/**
* This function will determine what is the data to be used for
* the Nth request we are generating, based on the input params.
*
* @param startIndex What is the index, in the roots list, that the
* chunk should start.
*/
_generateNextTranslationRequest(startIndex) {
let currentDataSize = 0;
let currentChunks = 0;
let output = [];
let rootsList = this.translationDocument.roots;
for (let i = startIndex; i < rootsList.length; i++) {
let root = rootsList[i];
let text = this.translationDocument.generateTextForItem(root);
if (!text) {
continue;
}
let newCurSize = currentDataSize + text.length;
let newChunks = currentChunks + 1;
if (newCurSize > MAX_REQUEST_DATA || newChunks > MAX_REQUEST_CHUNKS) {
// If we've reached the API limits, let's stop accumulating data
// for this request and return. We return information useful for
// the caller to pass back on the next call, so that the function
// can keep working from where it stopped.
return {
data: output,
finished: false,
lastIndex: i,
};
}
currentDataSize = newCurSize;
currentChunks = newChunks;
output.push([root, text]);
}
return {
data: output,
finished: true,
lastIndex: 0,
};
},
};
/**
* Represents a request (for 1 chunk) sent off to Google's service.
*
* @params translationData The data to be used for this translation,
* generated by the generateNextTranslationRequest...
* function.
* @param sourceLanguage The source language of the document.
* @param targetLanguage The target language for the translation.
*
*/
function GoogleRequest(translationData, sourceLanguage, targetLanguage) {
this.translationData = translationData;
this.sourceLanguage = sourceLanguage;
this.targetLanguage = targetLanguage;
this.characterCount = 0;
}
GoogleRequest.prototype = {
/**
* Initiates the request
*/
fireRequest() {
let key =
Services.cpmm.sharedData.get("translationKey") ||
Services.prefs.getStringPref("browser.translation.google.apiKey", "");
if (!key) {
return Promise.reject("no API key");
}
// Prepare the request body.
let postData = [
["key", key],
["source", this.sourceLanguage],
["target", this.targetLanguage],
];
for (let [, text] of this.translationData) {
postData.push(["q", text]);
this.characterCount += text.length;
}
// Set up request options.
return new Promise((resolve, reject) => {
let options = {
onLoad: (responseText, xhr) => {
resolve(this);
},
onError(e, responseText, xhr) {
reject(xhr);
},
postData,
};
// Fire the request.
this.networkRequest = httpRequest(URL, options);
});
},
};